Acetylcholinesterase-induced respiratory burst in macrophages: Evidence for the involvement of the macrophage mannose-fucose receptor

It has long been suggested that acetylcholinesterase is capable of functioning in a non-cholinergic manner. However, very little is known about the molecular structures which mediate the interaction between this protein and the cellular membrane. Previously it was demonstrated that acetylcholinesterase interacted in a carbohydrate-specific manner with peritoneal macrophages and induced the 'respiratory burst' [1]. This study aimed to establish whether a carbohydrate-binding site exists on the acetylcholinesterase molecule itself, or alternatively, whether the macrophage carbohydrate-binding receptor is involved. No carbohydrate binding properties intrinsic to acetylcholinesterase were detected using affinity chromatography with immobilised monosaccharides, erythrocyte agglutination and gel-diffusion techniques. The interaction between acetylcholinesterase and several monosaccharide columns observed in this study appeared to be due to ionic interactions. Moreover, it was shown that a specific inhibitor of the enzymatic activity of AChE, BW284C51, could inhibit the peritoneal cell response not only to acetylcholinesterase, but also to several other stimuli, thus exhibiting a non-specific effect on macrophages. However, the inhibitory effects of specific ligands of the macrophage mannose-fucose receptor and the inability of non-glycosylated acetylcholinesterase to interact with macrophages suggested that the effect of acetylcholinesterase on peritoneal cells is most probably mediated by the macrophage mannose-fucose receptor. The role of the mannose-fucose receptor in triggering the respiratory burst response was supported by the fact that several ligands of these receptors were capable of inducing the functional response of macrophages.